Unitary sanding and polishing machine



July l3, 1937. w; DAUM I 2,087,022.

UNITARY SANDING AND POLISHING MACHINE Filed Jan. 29, 1956 l .15 IINVENTOR. 16 18 dwmi fiflwm A TTORNEYS.

Patented July 13, 1937 UNITARY SANDING AND POLISHING MACHINE Edwin W.Daum, Louisville, Ky.

Application January 29, 1936, Serial No. 61,326

3 Claims.

In finishing welded and other rough surface portions of automobiles, itis customary, in automobile paint and repair shops, garages andfactories, to cut down the surface initially by means of an electricallydriven sanding machine. After this operation lacquer is usually sprayedon the sanded surface and the latter thereafter polished by means of anelectrically driven polishing machine. The sanding machine operates atarelatively high speed say 4,000R. P. M. While the polishing machineoperates at a lower speed usually in the neighborhood of 1,000 B. PpM.Except for these necessarily different operating speeds, both machineslargely have common requirements. They must be portable, i. e. easilycarried by hand; hence lightness in weight is highly desirable. Theymust also be capable of use around surfaces which are irregular in shapeand of restricted access; hence they should be small and compact.Furthermore they are apt to be handled by unskilled as well as skilledoperators with varying degrees of care; consequentl sturdiness is animportant factor.

The principal object of the present invention is to provide in a singleunit a machine which is capable of operation at a high speed as a sanderand at a lower speed as a polisher and to accomplish such objectivewithout sacrificing any of the requirements for such machines.

Another object is to provide a machine which may be easily and quicklychanged from either character to the other.

A further object is to provide a simple, compact and sturdy arrangementof gears connecting the driving motor to the working spindle and, incombination therewith, a simple and easily operated gear shift forchanging from one speed to another.

A further object is to provide a gearing which is self-locking in eitherof its different speed positions.

A still further object is to provide a structure of this character whichmay be easily assembled or disassembled.

A still further object is to provide a gear housing in which alloperating shafts are contained in the same plane and thereby facilitatethe ma chining of the shaft supporting parts of the housing to the endof reducing its cost of manufacture.

The invention is illustrated in the accompanying drawing wherein:

Figure 1 is a side elevation of a device constructed in accordance withmy invention;

Figure 2 is a top plan View thereof;

Figure 3 is a vertical longitudinal section taken through line 33 ofFigure 2;

Figure 4 is a transverse section taken along lines 4- of Figure 3.

Figure 5 is a vertical longitudinal section taken through line 5--5 ofFigure 2; and

Figure 6 is a perspective of the gear shift rod.

In carrying out the invention a driving motor l of any suitablecharacter is provided. A handle 2 is fixedly secured to one end of themotor, this handle preferably carrying a motor control switch 6 which isresiliently urged outwardly in any well known manner to the motor offposition. The motor drive shaft projects from the opposite end of themotor through an opening in a cross member or plate t which isinterposed between the motor and the gear housing 5. The plate 4 andhousing 5 may be detachably secured to the motor in any suitable manneras by the bolts ii. A handle I is detachably secured to one side of thegear housing and adapted for securement to the other side thereof so asto condition the machine for use by either right or left handedoperators.

The plate a and housing 5 cooperate to provide a support for a pair ofspaced parallel shafts 8 and 9 located on opposite sides of the motorshaft. These shafts preferably are arranged in the longitudinal or axialplane of the motor shaft because the corresponding shaft-receivingopenings and recesses in the plate and housing can then be machined orbored easier, quicker and with less skilled labor thus keeping themanufacturing cost at a minimum.

The motor shaft drives the shaft 8 through a spiral pinion l0 and spiralgear I! both of which are fixedly secured to their respective shafts.The shaft 8, in turn, is arranged to drive the shaft 9, at a low speed,through spiral driving gear l2 and driven gear 13 and, at a high speed,through spiral driving gear I2a and driven gear 13a. The spiral drivengears l3 and 13a, are fixedly mounted in spaced relation on the shaft 9while the spiral driving gears l2 and 12a are slidably mounted on theshaft 8 for movement from the low speed driving position through aneutral or non-driving position to the high speed driving position. Thespiral driving gears l2 and Her may be constructed and arranged in anysuitable manner but, as shown, the high speed gear iZa is simply fittedover and keyed to a peripheral portion of the low speed gear I2 thusmaking a composite unit of the two gears.

In connection with the high and low speed gearing above described it maybe pointed out that the gears may be made of any desired design. The useof spiral gears is preferred because they operate quietly with a minimumof vibration and because they are easier to move into meshing relationthan most if not all of the other available types of gears. While thespiral gears used may be arranged to exert their end thrust effect inone direction or another, I prefer to arrange the low speed spiral gears12 and i3 so that their end thrust effect is directed away from the highspeed position and to arrange the high speed gears I211 and l 3a so thattheir end thrust is directed away from the low speed position. In otherwords, with the arrangement illustrated in Figure 5, the end thrust ofthe low speed gears is directed to the right while that of the highspeed gears in Figure 3 is directed to the left. In this manner the lowand high speed gears tend to lock themselves in their respectiveoperating positions.

In order to shift the slidable gears from one position to another theslidable driving gear I2 is provided with a peripheral groove to receivea fork M which is fixedly secured to one end of a gear shift rod I5. Thelatter shaft passes successively through, and is supported by, apartition in the gear housing and the end wall of the housing. Thisshaft terminates, on the outside of the housing, in a detachable knobl6.

With self-locking gears in the high and low speed positions, it will beunderstood that the gears will normally remain in such positions exceptperhaps under unusual circumstances. As a further safeguard, however,additional locking means are provided for the high and low speedpositions which means are also made effective to lock the device in anintermediate or neutral position. Accordingly the gear shift rod I5 isprovided with three recesses H which are spaced from left to right atintervals corresponding to the high speed, neutral and low speedpositions of the gears. The rod is resiliently held, in any of thesepositions, by suitable means such as a spring pressed ball lock E8 ofany desirable type.

The two speed shaft 9 carries, at one end, a bevel pinion l 9 which isheld in fixed meshing or driving relation with a bevel gear 20 on thework spindle 2!. The spindle is located slightly beyond one end of theshaft 9 and is positioned at a right angle to, but in the plane of, theshaft 9. It extends from a partition in the housing outwardly through acap 22 which is detachably secured to the housing. The cap is made largeenough to permit the removal of the spindle and its bevel gear as a unitthrough the opening which is normally closed by the cap. The outer endof the spindle removably carries a sanding device 23 of the usual form.For polishing operation this head may be covered by a polishing cloth 24of the usual character.

It will be readily seen that the foregoing machine has the dualcharacters of both a sanding and a polishing machine and that it may beconverted from one to the other simply by appropriately shifting thegears and affixing or detaching the polishing cloth. Furthermore suchcharacters are attained without sacrificing any of the qualitiesdesirable in machines of this general character such as sturdiness,compactness, and portability. In this latter connection it may bepointed out that the machine described has been constructed with aweight of ten and one-half pounds which, as will be obvious, renders itexceptionally easy to carry and manipulate. Besides the self-lockingfeature, it has the further advantage of being exceptionally easy toassemble and disassemble. For example, upon removal of the bolts 6, theplate 4 and housing 5 may be separated from the motor and from eachother thus permitting the removal of shafts 8 and 9 with theirrespective gears, and rendering the removal of the gear shift rodsubject only to the detachment of its knob. As previously pointed out,the spindle can be removed simply upon removal of the bolts or othermeans by which the cap is held to the housing.

While the structure and operation of this device has been explained inconnection with its use as a sanding and polishing machine it will beunderstood that no limitation is intended thereby as it may be usedgenerally for the drilling of holes and various other purposes.

Having described my invention, I claim:-

1. A gear unit of the class described comprising a gear housing having aspindle, said housing being adapted for securement to a motor having adrive shaft, gearing within the housing for connecting the shaft to thespindle, said gearing including a pair of low and high speed gears whichare laterally shiftable between low and high speed positions, the lowspeed shiftable gear cooperating in the low speed position with anothergear to produce end thrust which is directed away from the high speedposition and the high speed shiftable gear cooperating in the high speedposition with another gear to produce end thrust which is directed awayfrom the low speed position, and manually controlled means for shiftingthe said gears from either position to the other.

2. A gear unit of the class described comprising a gear housing having aspindle, said housing being adapted for securement to a motor having adrive shaft, a pair of intermediate shafts rotatably mounted Within saidhousing, one intermediate shaft being connected to the drive shaft andthe other to the spindle, a pair of low and high speed spiral gearsmounted on each intermediate shaft, one pair of said gears beingshiftable laterally along its shaft from one position wherein the lowspeed gears of each pair mesh with each other to another positionwherein the high speed gears of each pair mesh with each other, the lowand high speed gears being relatively reversely spiraled so as toproduce reverse end thrust effects which respectively tend to maintainthe low and high speed gears in their respective low and high speedpositions, and manually controlled means for shifting the gears fromeither position to the other.

3. A portable machine of the class described comprising a motor having adrive shaft, a gear housing having a work spindle adjacent one end andbeing open at its other end which is removably securable to the driveend of said motor,

a member extending across the open end of said housing and having anopening through which the drive shaft of the motor projects into thegear housing when motor and housing are secured, said cross member beingremovable from the housing when motor and housing are unsecured, a pairof intermediate shafts extending axially within the housing and beingrotatably mounted at one end on said cross member and at the other endon a housing wall, one shaft being geared to the spindle and the otherto the motor drive shaft, interengageable shiftable multi-speed gearingmounted on said intermediate shafts, and an axially movable rodextending axially through the spindle end of the housing into engagementwith the shiftable gearing, said rod being manually operable to shiftthe gearing, said rod and intermediate shafts with the shiftable gearsattached being axially insertable into and removable from the housingthrough its open end when the cross member is removed therefrom.

EDWIN W. DAUM.

